Method for operating an emergency call system and emergency call system

ABSTRACT

An emergency call system and a method for operating the emergency call system are provided. The emergency call system includes a mobile device and receiving stations. The mobile device has a radio module to transmit an emergency call and each of the receiving stations is configured as a router and has an alarm device and a radio module to receive the emergency call. The emergency call is transmitted from the mobile device to a first receiving station to trigger the alarm signal and a position of the mobile device relative to the receiving stations is determined. Depending on the position, only one of the receiving stations is selected to trigger the alarm signal.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. patentapplication Ser. No. 15/178,346 filed on Jun. 9, 2016, which is acontinuation application of international patent applicationPCT/EP2014/077016, filed Dec. 9, 2014, designating the United States andclaiming priority from German application 10 2013 225 325.7, filed Dec.9, 2013, and the entire content of these applications is incorporatedherein by reference.

TECHNICAL FIELD

The invention relates to an emergency call system and a method foroperating the emergency call system. The emergency call system includesat least one mobile device having at least one radio module fortransmitting an emergency call and a plurality of receiving stations,each having at least one radio module configured for receiving theemergency call.

BACKGROUND

In the related art, a large number of different emergency call systemsis described which transmit an emergency call via a radio network. Inthis regard, the German utility model DE 296 19 164 U1, for example,describes an emergency call system that includes a plurality ofinstalled receiving stations. A mobile device, such as a watch or apager, for example, can transmit an emergency call that is detected by areceiving station, and that is forwarded to an emergency call center. Asa result, a casualty, for example, can rapidly be given help in the formof a dispatched emergency ambulance or the like. However, this system isunsuitable for emergency cases in which the user of the mobile device isin a dangerous situation caused by another person, for example.Moreover, the user has to wait for the requested help to arrive. Even ifthe user of the mobile device is threatened by another person, theemergency call generated by the emergency call system does not provideimmediate help since the emergency call system must firstly be forwardedto the emergency call center and the emergency call center must send apolice officer or the like to the position of the person making theemergency call.

A system as described in U.S. Pat. No. 7,541,921, for example, istherefore better suited in dangerous situations. The document proposesthat an emergency call transmitter transmits a signal to a plurality ofreceiving stations integrated in motor vehicles, wherein the receivingstations, as a reaction to the alarm signal, firstly forward theemergency call to a monitoring center and secondly emit sound or lightsignals as alarm signal by the vehicle electronics in order to attractattention and to chase away a perpetrator, for example. If a pluralityof vehicles with corresponding equipment is in relatively closeproximity, then the alarm is triggered in all of these vehicles. This,however, makes it more difficult to carry out an unambiguousidentification of the location at which the user of the mobile device issituated.

United States patent application publication 2013/0057401 A1additionally describes an emergency call system in which a radio moduletogether with an alarm device are provided as one unit. In this case, ifan alarm is triggered, firstly the alarm device generates an alarmsignal and secondly the radio module is activated in order to transmitstructural data, for example regarding the building in which the unit isprovided, so that, in the case of an emergency, helpers can rapidlyobtain information about the building. In this case, however, the alarmis triggered manually directly in the unit before a radio connection ispossible.

SUMMARY

An object of the invention is to provide an emergency call system which,in a dangerous situation, helps the user as rapidly as possible bydirecting attention to the user in particular by a targeted generationof an alarm signal.

The object is achieved by providing an emergency call system and amethod for operating the emergency call system including: transmittingthe emergency call from the at least one mobile device to a first of theplurality of receiving stations to trigger the alarm signal; determininga position of the at least one mobile device relative to the pluralityof receiving stations; and, depending on the determined position of theat least one mobile device, selecting only one of the plurality ofreceiving stations to trigger the alarm signal.

The method according to an aspect of the invention has the advantagethat the triggered alarm signal directs the attention of third partiesto the user of the mobile device in a targeted manner. In this case, thealarm can even be triggered by a person who is not directly exposed tothe danger but would like to draw attention to the danger regardinganother person, without revealing himself/herself and thereby possiblyexposing himself/herself to the danger.

According to another aspect of the invention, each receiving station hasan alarm device for outputting an alarm signal, and the mobile device,in order to trigger the alarm, transmits an emergency call to a firstreceiving station, in particular only to a first of a plurality ofreceiving stations, wherein a position of the mobile device relative tothe receiving stations is determined and, depending on the determinedposition, only one of the receiving stations is selected for outputtingthe alarm signal by the respective alarm device. It is thereforeprovided that an alarm device of only one receiving station outputs thealarm signal. This receiving station is selected depending on theposition of the mobile device relative to the receiving stations, suchthat in particular the receiving station best suited to the purposegenerates the alarm signal. The alarm or the alarm signal is generatedby the receiving station that is selected depending on the determinedposition in such a way that the attention of third parties cannot beconfused by further alarm signals and the actual position of theemergency call generator can be detected more rapidly.

According to another aspect of the invention, the emergency call systemhas a full coverage configuration. For this purpose, the receivingstations of the emergency call system are arranged in a predefined areain a distributed manner in such a way that no matter where the mobiledevice is located in the area, an emergency call can always betransmitted to at least one of the receiving stations. According to afurther aspect of the invention, the first receiving station, that hasreceived the emergency call, forwards the latter directly to amonitoring center or to a central server. For this purpose, thereceiving stations are expediently connected wirelessly or in a wiredmanner to a local area network (LAN) in which the central server is alsolocated.

According to yet another aspect of the invention, it is provided thatthe mobile device, in particular by its radio module, determines signalstrengths of the radio modules of the receiving stations and transmitsthe emergency call to the receiving station whose radio module has thehighest signal strength. Therefore, if the mobile device is actuated inorder to transmit an emergency call, then firstly signal strengths ofthe available receiving stations are detected. For this purpose, themobile device scans or senses its surroundings and correspondinglyevaluates the detected data. The fact that the mobile device transmitsthe emergency call to the receiving station having the highest signalstrength ensures that the emergency call is transmitted securely andrapidly to the receiving station that is probably located at the mostexpedient location. Specifically, it can generally be assumed that thereceiving station having the highest signal strength is the receivingstation arranged nearest to the mobile device.

According to another aspect of the invention, the first receivingstation that receives the emergency call detects a signal strength ofthe radio module of the mobile device and determines the position of themobile device depending on the signal strength. It is assumed here thatthe transmission power of the radio module of the mobile device is knownin principle. Accordingly, it is possible for the receiving station todetermine at least the distance between the mobile device and therespective receiving station depending on the detected signal strength.If the receiving station additionally has a corresponding directionalcharacteristic of its radio module, then the position of the mobiledevice relative to the receiving station can be determined sufficientlyaccurately. Alternatively or additionally, the position of the mobiledevice is determined by triangulation. For this purpose, the firstreceiving station communicates with neighboring receiving stations thatare likewise within the range of the mobile device and can detect thesignal strength thereof. Through knowledge of the arrangement of thereceiving stations relative to the first receiving station, it isthereby possible to ascertain the position of the mobile devicesufficiently accurately by triangulation. If only two receiving stationsare located in the radio range of the mobile device, then a sufficientlyhigh positional accuracy can be achieved by these two receivingstations. With such a procedure, in particular a cost intensivedirectional characteristic of the radio module of the receiving stationscan be dispensed with.

According to an alternative aspect of the invention, the mobile devicetransmits to the first receiving station the detected signal strengthsof all detected receiving stations with the emergency call, wherein thefirst receiving station determines the position of the mobile devicedepending on the signal strengths. Here, therefore, the calculation ordetermination of the position of the mobile device depending on thesignal strengths takes place by the receiving station which receivesnotification of the signal strengths of the neighboring receivingstations that were likewise detected by the mobile device. As a result,all information for determining the position of the mobile device isavailable to the first receiving station.

In accordance with another aspect of the invention, the detected signalstrengths are compared by the first receiving station with one or morereference signal strengths, wherein the first receiving station triggersthe alarm signal by the alarm device only if the detected signalstrengths correspond to one or more of the reference signal strengths.In order to locate the mobile device more rapidly, the position of themobile device is not calculated, but rather determined by datacomparison. For this purpose, the reference signal strengths are storedbeforehand in a memory of the respective receiving station, for examplein a characteristic curve or in a family of characteristic curves.Depending on a detected signal strength, a corresponding position canthen be determined rapidly.

When setting up the emergency call system the reference signal strengthsare determined individually for the respective receiving station byvirtue of a reference mobile device transmitting test signals or testemergency calls at different positions relative to one or more of thereceiving stations, in a known position of the mobile device withrespect to the receiving station. Accordingly, the respectively detectedreference signal strength is then stored together with the knownposition in the respective receiving station, or in a central serverconnected to the receiving stations, for later use. Furthermore, forsetting up the emergency call system at different positions, a referencesignal strength of a reference mobile device respectively detected bythe receiving stations is stored together with position data of thereference mobile device determined by a global navigation satellitesystem. By taking account of global navigation satellite system data, itis also possible to represent or determine the position of the mobiledevice in a digital map, for example by indications regarding longitudeand latitude. As a result, the position of the mobile device can bedetermined very accurately by detecting the signal strengths andcomparing them with the reference signal strengths. The reference signalstrengths are combined or divided into reference signal strength ranges,and upon detection of an emergency call, the detected signal strengthsare compared with the reference signal strength ranges in order todetermine the position of the mobile device.

After receiving the emergency call, the first receiving station forwardsat least the emergency call, an identifier of the mobile device and theposition of the first receiving station and/or of the mobile device tothe central server. The emergency call is forwarded to a central serveror to a monitoring center which forwards the data to the securityservice or to the police authority, for example, at least if anemergency call by an authorized user is involved. If the position of themobile device was determined as described above, an accurate position ofthe person making the emergency call can thus also simultaneously beforwarded by the emergency call center. Expediently, the emergency callis forwarded to the central server directly after reception by the firstreceiving station, while, if appropriate in parallel therewith the firstreceiving station determines whether the first receiving station or oneof the neighboring receiving stations should output the alarm signal.

In accordance with another aspect of the invention, for setting up theemergency call system when determining the reference signal strengthsdepending on the position of the mobile device, one of a plurality ofreceiving stations located within range is preselected for triggeringthe alarm signal. If, as described above, the emergency call system isset up the reference mobile device, one of the receiving stations ispreselected, depending on the respective position of the mobile deviceor of the reference mobile device, in order to trigger an alarm signalif a corresponding mobile device is located at the correspondingposition and transmits an emergency call. What is achieved thereby isthat it is not necessarily the receiving station having the highestsignal strength that generates/outputs the alarm signal, but rather thereceiving station that is best suited to the respective situation. Thisis of importance, for example, if the first receiving station, althoughcloser to the mobile device, is located behind a wall or the like, whilea second receiving station, which is somewhat further away, is in thevisual range of the mobile device or of the user of the mobile deviceand would thus be better suited for triggering the alarm.

In accordance with a further aspect of the invention, when setting upthe emergency call system position, data of neighboring receivingstations are stored in the receiving stations, wherein the firstreceiving station, depending on the position of the mobile device,itself triggers the alarm signal or instructs a neighboring secondreceiving station to trigger the alarm signal if the second receivingstation is nearer to the detected position of the mobile device than thefirst receiving station or if the second receiving station is thepreselected receiving station. Therefore, the receiving stationspreferably also communicate among one another. If the emergency call iscommunicated to the first receiving station, the latter decides whetherit itself triggers the alarm or forwards the emergency call to a secondreceiving station, if the latter is better suited thereto on account ofthe position of the mobile device. The data regarding the positionsand/or the signal strengths or reference signal strengths may beprovided for retrieval both in the respective receiving station itselfand in the central server.

According to a further aspect of the invention, the receiving stations,by their respective radio module, scan their surroundings in order todetect and to confirm neighboring receiving stations. The fact that thereceiving stations also detect the signal strengths of neighboringreceiving stations makes it possible to achieve a safeguarding of theemergency call system overall in such a way that the removal of areceiving station is registered by the remaining receiving stations. Asa result, for example, a theft of a receiving station can be rapidlyrecognized or even prevented.

According to an aspect of the invention, the receiving station triggersa silent alarm or a loud alarm depending on the transmitted emergencycall. In this case, the mobile device is configured to transmitdifferent emergency calls that correspondingly lead to a silent alarm orto a loud alarm. For this purpose, the mobile device expediently has atleast one emergency call switch, upon the actuation of which theemergency call is transmitted. In this case, an emergency call forgenerating a loud alarm signal is triggered upon a single actuation andan emergency call for generating a silent alarm signal is triggered upondouble actuation. Optionally, the emergency call switch is covered by asafety cap or the like which has to be removed before the emergency callswitch is actuated. This prevents inadvertent actuation of the emergencycall switch in a simple manner. In the event of a silent alarm beingtriggered, only the data such as the user identifier or the mobiledevice identifier and also the detected position of the mobile device orof the first receiving station are forwarded to the central server,without an audible or visible alarm signal being triggered. This makesit possible to prevent a premature escalation of a dangerous situationbefore helpers arrive.

Expediently, therefore, a user identifier or a mobile device identifierfor identifying the user is concomitantly transmitted with the emergencycall by the mobile device to the first receiving station. As a result,the emergency call can also be directly assigned to a person. Inparticular, it is thereby possible to check the authorization of theperson to use the emergency call system.

According to yet another aspect of the invention, it is provided thatthe mobile device, starting from the transmission of the emergency call,starts an audio recording and transmits audio data packets at regularintervals to the first receiving station and/or to another receivingstation. The audio recording is intended to document the situation andto communicate it to the monitoring center via the receiving station,for example. As a result, the monitoring center is kept up to date withregard to the situation and can give targeted help. What is achieved bythe preferred transmission of audio packets at regular intervals is thatthe susceptibility to errors for relatively large files that have to betransmitted is reduced. Dividing the recording into individual packetsincreases the reliability of the monitoring center receiving the audiofile such that the latter is undamaged and usable.

According to an aspect of the invention, an alarm signal is triggeredonly if the user identifier or mobile device identifier corresponds toan authorized user identifier or mobile device identifier stored in thecentral server or in the first receiving station. As already mentionedabove, what is achieved thereby is that a use of the emergency callsystem by an unauthorized person is prevented. Furthermore, it isensured that the emergency call can be assigned to a specific person, asa result of which, for example, an announced test of the emergency callsystem by a user may be carried out or misuse of the emergency callsystem, although not prevented, is nevertheless trackable.

In accordance with an additional aspect of the invention, if the mobiledevice is located in surroundings in which the nearest receiving stationis outside its radio range, that is, that the emergency call of themobile device cannot be received by a receiving station, the mobiledevice sets up a wireless communication connection to a cellular phonethat is within its range, and in so doing or as a result controls thecellular phone to start an emergency call to a monitoring centerautomatically via a mobile radio network via which the cellular phonecommunicates. In this case, the mobile device, which transmits theemergency call to the receiving station by WLAN, if there is noreceiving station within its range, controls a further radio module,which allows a different type of wireless communication, in particular aBluetooth module, in order to transmit the emergency call in a differentwireless manner. The fact of whether an emergency call was transmittedsuccessfully to a receiving station can be confirmed for example by anacknowledgement message of the receiving station to the mobile device.If this confirmation fails to occur after the mobile device hastransmitted the emergency call, then it changes its operating mode andcontrols the other radio module, in particular the Bluetooth modulealready mentioned, in order to transmit the emergency call via adifferent communication network. Alternatively, the mobile devicetransmits the emergency call to the cellular phone by the radio modulealready present. Preferably, the cellular phone of the user who alsocarries the mobile device is set up for a corresponding connection, inparticular Bluetooth connection, to the mobile device beforehand, sothat the mobile device automatically establishes the connection to thecellular phone of the user and the cellular phone of the user transmitsthe emergency call to the monitoring center. In this case, position dataprovided by the cellular phone and/or by the mobile device are likewiseforwarded to the monitoring center via the emergency call in order toachieve the advantages and possibilities already described above.

The emergency call system according to an aspect of the invention, isconfigured in particular as a full-coverage emergency call system. Eachreceiving station has an alarm device and a control unit, wherein thealarm device is configured to output an alarm signal, and wherein thecontrol unit, depending on a signal strength, determines a position ofthe mobile device and, depending on the determined position, triggersthe alarm signal. This affords the advantages already mentioned above.In this case, the emergency call system is configured, in particular, tocarry out the method described above.

According to an aspect of the invention, each receiving station isconfigured as a WLAN router. Accordingly, the receiving station has, asa radio module, a WLAN module that is used for receiving the emergencycall. Accordingly, the at least one mobile device likewise has a WLANmodule as a radio module in order to set up the communication connectionto the receiving station. The emergency call system thus providesrouters having full coverage which can also be used for internetconnections or for providing information via the WLAN. As a result, therouters fulfill not only the security aspects of the emergency callsystem but also further functions that can be used by users of theemergency call system or else by third-party providers. In accordancewith a further aspect of the invention, the radio modules are configuredas Bluetooth modules. It is also conceivable to use some other knownradio standards for data transmission.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described with reference to the drawingswherein:

FIG. 1 shows an emergency call system in a simplified illustrationaccording to an exemplary embodiment of the invention;

FIG. 2 shows a mobile device of the emergency call system;

FIG. 3 shows a receiving station of the emergency call system;

FIG. 4 is a flow chart illustrating the setup and use of the emergencycall system according to an exemplary embodiment of the invention; and,

FIG. 5 is a flow chart illustrating the use of the emergency call systemaccording to an exemplary embodiment of the invention.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

FIG. 1 is a simplified illustration of an emergency call system 1. Theemergency call system serves to increase the safety of users of theemergency call system 1 in dangerous situations, such as, for example,in the case of an attack, an accident or the like. For this purpose, theemergency call system 1 includes a mobile device 3 carried by therespective user, and also a plurality of local or stationary receivingstations 4, 5, 6, only three of which are illustrated in the exemplaryembodiment. The emergency call system 1 is expediently configured as afull-coverage emergency call system 1, such that the receiving stationsare arranged in a distributed manner across a large area. Particularlyin cities, the emergency call system 1 can contribute to the citizens'safety. However, corresponding receiving stations may be arrangedoutside the cities, so that the emergency call system 1 is also usableand advantageous for its users outside the cities.

FIG. 2 shows a perspective illustration of the mobile device 3 accordingto an exemplary embodiment that is made available to each user of theemergency call system 1. Each user thus has a mobile device of thistype. The mobile device 3 is configured as a USB stick which is usablewith a USB connection 7 for data and energy transmission and which canbe covered by a cover illustrated in FIG. 2. Furthermore, the mobiledevice has an emergency call switch 8, which in the exemplary embodimentshown in FIG. 2 is configured as a pushbutton. The emergency call switch8 is assigned an optional safeguard slide 9 which, in one slidingposition, as illustrated in FIG. 2, raises the emergency call switch 8and, in another sliding position, covers the emergency call switch 8 inorder to prevent inadvertent actuation of the emergency call switch 5.Besides a rechargeable energy store (not illustrated in FIG. 2), themobile device 3 additionally has a radio module 10, which is configuredas a WLAN module (WLAN=wireless local area network) for transmittingand, if appropriate, also for receiving data.

If the user 2 actuates the emergency call switch 8, then an emergencycall is transmitted to one of the receiving stations 4 to 6 by the radiomodule 10.

FIG. 3 is a simplified illustration of the receiving station 4, whereinthe receiving stations of the emergency call system 1 are preferablyconstructed identically, such that the explanations concerning thereceiving station 4 also apply to the receiving stations 5 and 6 and allfurther receiving stations of the emergency call system 1.

Each receiving station has a radio module 11, which is likewiseconfigured as a WLAN module and serves for receiving the emergency call.In this case, the radio module 11 is always activated, such that theradio module 11 or the respective receiving station 4, 5 or 6 isidentified as a so-called WLAN hotspot. In this case, each of thereceiving stations of the emergency call system 1 is configured as arouter, so that each receiving station 4 to 6 is connected to a localarea network in order to transmit data from and to a central server 12,as is indicated in FIG. 1. As a result, the receiving stations 4 to 6are connected to the central server 12 for a data exchange, inparticular in order to forward an emergency call triggered by the mobiledevice 3 to the central server 12.

Each of the receiving stations 4 to 6 additionally has a control unit13, and also an alarm device 14, which is configured for generating anacoustic alarm signal. For this purpose, the alarm device 14, as shownin FIG. 3, includes a loudspeaker 15. Alternatively or additionally,however, the alarm device 14 may have an illuminant for generating avisual alarm signal.

If the user 2 triggers an emergency call by actuating the emergency callswitch 8, the emergency call is transmitted to one of the receivingstations 4 to 6 by radio or WLAN, and one of the receiving stations 4 to6 triggers the alarm signal by its alarm device 14. The emergency callsystem 1 thus makes it possible for the user 2 to trigger an alarmsignal at one of the receiving stations 4 to 6 of the emergency callsystem 1 by actuating his/her mobile device 3. As a result, theattention of third parties is immediately directed to the occurrence, asa result of which, for example, an attack on the user 2 is prevented orat least terminated by the perpetrator(s) being frightened off andstartled. In order to afford the greatest possible protection for theuser, the emergency call system 1 is firstly configured as illustratedin FIG. 4.

FIG. 4 is a flow chart illustrating the setup of the emergency callsystem 1 when the receiving stations 4 to 6 have already been installedwith full coverage over a predefined area and, in particular, when thereceiving stations are installed and arranged in such a way that afull-coverage WLAN network is made available in the area by therespective radio modules 11 of the receiving stations. After thereceiving stations have been installed and, in particular, have beenconnected to the local area network, the following operations areperformed.

Firstly, by a reference mobile device, which is also configured like themobile device 3, a reference system is established in step 16. For thispurpose, a technician positions the reference mobile device at variouspoints in the area and scans or senses the surroundings for receivingstations present by the radio module of the reference mobile device.According to a first exemplary embodiment, a technician stands with thereference mobile device for example on various points of the street andthen scans the surroundings in each case. The reference mobile deviceadditionally has a location determining device that interacts with aglobal navigation satellite system in order to assign position data tothe respective position. At each of the reference points at which thetechnician carries out the reference measurement, location data, forexample GPS data, are thus also stored. During the scanning of thesurroundings, the signal strengths of the radio modules 11 of thereceiving stations 4 to 6 that are located within range are determined.An identifier of the respective receiving station is also determined andstored together with the position in step 18. Alternatively, thereceiving stations 4 to 6 detect the signal strength of the referencemobile device 3 and store it as a reference signal strength togetherwith the position detected by the global navigation satellite systemand/or transmit it to the central server 12 in order to store it there.A subsequent step 19 involves determining which receiving station at therespective position of the reference mobile device is most likely totrigger the alarm signal. In this case, the receiving station thatoffers the highest protective effect for the user 2 of the emergencycall system 1 is selected during the set up depending on the position ofthe reference mobile device. This takes into account, that the presentsituation may involve the case, for example, that in a specific positionthe receiving station closest to the user 2 is not in the visual rangeof the user, but rather hidden for example behind a house wall, a fence,a row of trees or the like. In this case, it is more expedient if one ofthe receiving stations 4 to 6 which is within the visual range of theuser 2 triggers the alarm signal, such that third parties who hear orsee the alarm signal originated from the receiving station transmittingthe alarm signal, may also directly detect the user 2 and thus thedanger and possibly rush to give aid.

During set up, depending on the respective reference point, depending onthe detected reference signal strengths of the receiving stations 4 to6, and also depending on the actual arrangement and suitability of therespective receiving station, an optimum receiving station ispreselected in step 19.

After recording the reference points in accordance with step 16, theinformation obtained thereby is stored in step 20 and transmitted to thecentral server 12 in step 21. Reference regions, which relate to therole or “responsibility” of the respective receiving station, are formeddepending on reference points. In this regard, reference points arecombined into reference regions, for example, and assigned to one of thereceiving stations as regions of responsibility. The central server 12stores the collected information in a database and contacts allreceiving stations whose identifier was detected during theestablishment of the reference points or reference regions in step 22 inorder to communicate subsequently the information about the referencepoints and the signal strengths associated therewith to the receivingstations in step 23.

Upon the start-up of the emergency call system 1, in step 24 thereceiving stations 4 to 6 calculate on the basis of the data now stored,depending on the respective reference point and/or reference region,which of the receiving stations is optimally suited for triggering thealarm signal, subject to the preselection carried out in step 19. Forthis purpose, the control unit 13 of the receiving stations or thecentral server 12 determines the region of responsibility for therespective receiving station by the in step 25. For this purpose, asignal strength range of reference signal strengths in which therespective receiving station ought to trigger the alarm signal isdetermined in step 26. This is carried out depending on the strength ofthe signal strengths and the preselection carried out in step 13. If nopreselection is carried out, then the receiving station having thehighest signal strength which was detected in relation to the respectivereference point is selected. The reference signal strengths or referencesignal strength ranges are preferably calculated by each receivingstation for itself and preferably also for at least one neighboringreceiving station.

If an emergency call is triggered, then the respective receiving stationdetermined, in step 27, whether it is located in the region ofresponsibility, or whether the emergency call signal in accordance witha signal strength is within the reference signal strength range. If thealarm is triggered in the region of responsibility of the receivingstation, then the alarm is triggered in step 28. If the detected signalstrength is not in the signal strength range or if the emergency call isnot triggered in the region of responsibility of the receiving station,the latter determines, in a subsequent step 29, in what region ofresponsibility the emergency call was transmitted, and transmits thedata to the corresponding receiving station, which then determines, instep 25 and/or step 27, whether it is located in the region ofresponsibility.

If no matching region or responsibility is found, then the receivingstation that is the first to receive the emergency call determines instep 30 which of the neighboring receiving stations has a region ofresponsibility that is closest to the emergency call signal. If thereceiving station is not itself the one whose region of responsibilityis closest to the emergency call signal or the mobile device 3, then instep 31 the first receiving station communicates the data communicatedby the emergency call to the matching receiving station whose region orresponsibility is closest to the emergency call signal, such that thisreceiving station triggers the alarm in step 28. This second receivingstation that obtains the emergency call through the first receivingstation proceeds to steps 25 to 31 in order to determine whether ititself is suitable for triggering the alarm signal or whether it isactually in the relevant region of responsibility or closest thereto.

The operation of the emergency call system 1 according to an exemplaryembodiment of the invention will be explained below with reference toFIG. 5. The situation illustrated in FIG. 1 is taken here as a basis, inwhich the user 2 is located on a path 32 from which a path 33 branchesoff, the user 2 being located at the branching point. In this location,the receiving stations 5 and 4 are in visual range of the user 2, whilethe receiving station 6 is hidden by a building structure 34. Apart fromthe building structure 34, still further building structures 35 areprovided as well, but do not lie between the user 2 and one of thereceiving stations 4 or 5.

If the user 2 approaches an unknown person or it is apparent to the user2 that the latter will be attacked, or the user 2 is in an emergencysituation of some other type, such as an accident, for example, then ina first step 36 the user 2 actuates the mobile device 3, in particularby firstly sliding the safeguard slide 9 toward the side, in order toexpose the emergency call switch 8, and then pressing the emergency callswitch 8. In a subsequent step 37, the mobile device 3 determines whatkind of actuation is involved.

The mobile device 3 likewise has a control unit (not illustrated in FIG.2) that differentiates between different types of emergency callsdepending on the actuation of the emergency call switch 8. Inparticular, this involves differentiating whether the alarm ought to bea loud alarm or a silent alarm. In this regard, if the emergency callswitch 8 is briefly actuated only once, an emergency call is immediatelytransmitted for triggering a loud alarm, that is, for triggering anacoustic alarm signal. If the emergency call switch 8 is actuated oncemore within a maximum of two seconds, for example, then it is recognizedthat a silent alarm ought to be triggered, in the case of which, forexample, as alarm signal, a visual warning and/or a notification isforwarded to the central server 12 or to the emergency call center. Thesilent alarm may be advantageous for example if a dangerous situation isintended not to escalate prematurely or before helpers arrive.

Advantageously, as illustrated in FIG. 2, the mobile device 3additionally has a microphone 38, by which the mobile device 3 canrecord ambient sounds. Depending on the actuation of the emergency callswitch 8, the user 2 can additionally determine whether an audiotransmission of the event ought to be carried out in addition to theemergency call. In this case, if the user keeps the emergency callswitch 8 pressed upon the first or second pressing, the microphone 38 isnot activated or an audio recording is not started. In the present casethis results in different basic functions of the mobile device 3depending on the actuation of the triggering switch or emergency callswitch 8. In a first basic function B1, a loud alarm is triggered, andthe audio recording is activated. In a second basic function B2, asilent alarm is triggered, and the audio recording is activated. In athird basic function B3, a silent alarm is triggered without an audiorecording being carried out, and in the fourth basic function B4, a loudalarm is triggered without an audio recording being carried out.

It is also conceivable, of course, to limit the functionality to onlyone or two basic functions, such that the user only has a choice betweena loud and a quiet alarm, wherein the audio recording is started asstandard, for example.

When an audio recording is desired, the microphone continuously recordsambient sounds. In this case, data audio packets of 5 seconds, forexample, are generated which are transmitted by the radio module of themobile device 3 together with the emergency call and in particular alsoafter the transmission of the emergency call to the respective receivingstation. That means that for example in each case only the last 5seconds are communicated every 5 seconds to the respective receivingstation 4 to 6, rather than the complete recording. As a result, theentire audio recording is communicated in a manner divided into aplurality of sections. This achieves the advantage that if the user 2moves out of the reception range of the respective receiving station 4to 6, as a result of which the audio transmission might be interrupted,it is ensured that as much sound recording as possible is communicatedto the receiving station. The receiving station 4, 5 or 6 that receivesthe signal preferably likewise records a sound signal and forwards thelatter together with the audio packet generated by the mobile device 3to the central server 12. As a result, firstly, evidence material issafeguarded and, secondly, a person in the emergency call center canappraise the urgency of the emergency call and the dangerous situationpresent.

According to an exemplary embodiment, the mobile device 3 is configuredin such a way that an electrical connection of the radio module 10 tothe energy store already mentioned above is generated only upon theactuation of the emergency call switch 8, such that after charging ofthe energy storage (battery), the latter provides energy over a verylong period of time until the mobile device 3 is used for the firsttime. This ensures that the mobile device 3 is available for a long timeafter charging.

After the start-up of the mobile device 3 by the user 2 in a step 38,the mobile device 3, by the radio module 10, scans the surroundings forreceiving stations located in the vicinity. Since the radio modules 11of the receiving stations 4 to 6 are always activated, the radio module10 of the mobile device 3 detects the receiving stations 4 to 6 if theyare in the vicinity. In this case, in step 39, the mobile device 3detects the identifiers of the receiving stations in the vicinity andalso the signal strength of the respective receiving station or of therespective radio module 11. Next, in step 40, the mobile device 3selects one of the receiving stations 4 to 6 to which it transmits theemergency call. This first receiving station is selected by the mobiledevice 3 in step 41 depending on the detected signal strengths and/ordepending on the point in time at which the mobile device 3 detected therespective receiving station 4 to 6. According to an exemplaryembodiment of the invention, the mobile device 3 selects that receivingstation of the receiving stations 4 to 6 which has the highest signalstrength. This ensures that the audio recording or the audio datapackets can also be transmitted most rapidly and most securely. If themobile device 3 is actuated in order to trigger an alarm without anaudio recording (for example B3 or B4), as an alternative, the mobiledevice 3 selects the receiving station that it reaches first. In theexemplary embodiment in accordance with FIG. 1, the receiving stationlocated the closest is the receiving station 6 (line of flight). If thebuilding structure 34 is correspondingly transmissive, it is assumedthat the same radio module having the same transmission power isinstalled in each case in the receiving stations, and thus for themobile device 3 the receiving station 6 is the one having the highestsignal strength. Accordingly, the receiving station 6 is selected as thefirst receiving station.

Subsequently, in step 42, the mobile device 3 transmits the emergencycall and the collected data, namely the identifier and the signalstrength of the receiving stations which it has detected, to the firstreceiving station via the radio module 10. The previously collected datatogether with the emergency call and/or the desired type of alerting aretransmitted to the first receiving station 6 in step 43. In step 44, theaudio data packets are transmitted in a corresponding previouslyselected time frame from the mobile device 3 to the receiving station 6.As soon as the first receiving station 6 has received the data, thelatter are processed in step 43 in accordance with substeps 44 to 49 andare forwarded immediately directly to the central server 12. Firstly, anidentifier of the mobile device 3 that was concomitantly transmittedwith the emergency call, the signal strengths of the receiving stations4 to 6 detected by the mobile device 3, and also the identifiers of thereceiving stations 4 to 6 are detected and forwarded to the centralserver 12 in step 44.

Subsequently or in parallel therewith, in substep 45, the receivingstation 6, as described above with reference to FIG. 4, determineswhether it is the correct one to trigger the alarm signal. For thispurpose, it compares the signal strengths detected by the mobile device3 with the stored reference signal strengths or reference signal rangesdetected during the setting up of the emergency call system 1, in orderto determine whether the first receiving station 6 itself ought totrigger the alarm signal. This also takes account of whether one of thereceiving stations 4 or 5 likewise detected by the mobile device 3 wasdetermined as the preselected receiving station during the setting up ofthe emergency call system 1. For this purpose, the position of themobile device 3 is determined on the basis of the signal strengths. Inthis case, the detected and communicated signal strengths are comparedwith the reference signal strengths or reference signal ranges, whereinthe reference signal strengths or reference signal ranges, as describedabove, are stored together with location data of the respectivereference point. Consequently, the actual position of the mobile device3 can also be deduced by evaluating the detected signal strengths.Moreover, it is conceivable to calculate the position of the mobiledevice 3 on the basis of triangulation and the detected signalstrengths. If the receiving station 6 determines that the detectedposition substantially corresponds to the position of a reference pointor reference region assigned to a preselected receiving station fortriggering an alarm signal, then the first receiving station 6 forwardsthe emergency call to the preselected receiving station.

According to an exemplary embodiment of the invention, the receivingstation 4 is determined as the preselected receiving station for theposition of the user 2 since it is within the visual range of the user 2and on the path on which the user 2 is located. The receiving station 4is thus best suited to trigger the alarm signal since attention canthereby be directed to the user 2 most rapidly. Consequently, in theexemplary embodiment of the invention, the first receiving stationforwards the emergency call to the receiving station 4 (step 46).

The second receiving station 4 thereupon confirms receipt of the data tothe first receiving station 6 in step 47. When the second receivingstation 4 is not in the reception range or transmission range of thefirst receiving station 6, the first receiving station transmits thedata to the central server 12, which thereupon contacts the secondreceiving station 4. If this goes wrong, the first receiving station 6triggers the alarm signal (substep 48).

When the second receiving station 4 does not confirm receipt of the datawithin a specific period of time, even if the second receiving station 4is in the transmission range of the first receiving station 6, the firstreceiving station 6 likewise contacts the central server 12 in order toreach the second receiving station 4 via the latter in accordance withstep 48 (substep 49).

Depending on the respectively desired alarm signal (B1 to B4), thecorresponding receiving station 4 or 6 then initiates a silent or loudalarm by the respective alarm device 14. The silent alarm is preferablyaccompanied by a visual alarm signal in order to facilitate orientationfor helpers alerted by the silent alarm upon arrival in the region ofthe event.

The mobile device 3 may be equipped optionally with an NFC device 50(NFC=near field communication), illustrated by dashed lines in FIG. 2,which serves for activating the mobile device 3. In order to achieve ahigh security, it must be ensured that an emergency call can only betriggered by authorized mobile devices 3. Each mobile device 3 providedfor the emergency call system 1 is provided with an identifier, asalready mentioned. If a mobile device is purchased in a shop, then themobile device 3 is preferably activated by the mobile device 3 beingattached to an NFC device and the emergency call switch 8 beingactuated. In this case, the mobile device 3 is configured in such a waythat in the vicinity of an NFC device preferably no emergency call istransmitted, or no alarm is triggered. The NFC device is connected to arouter of the shop which forwards the enquiry for activation to thecentral server 12. The latter transmits the confirmation back to the NFCdevice if the identifier of the NFC device and the identifier of therouter of the shop correspond to the identifiers stored in the centralserver. For this purpose, the system knows what mobile device 3 withwhat identifier was transmitted to what shop with what router identifierand with what NFC device identifier. It is thereby possible to ensurethat the mobile device 3 is activatable only by an authorized shop.

In addition, the receiving stations 4 to 6 communicate among oneanother. In particular, each of the receiving stations 4 to 6 regularlyscans its surroundings for neighboring receiving stations. If thisprocess detects that one of the known receiving stations, which areknown for example as a result of a previous scan or whose position andsignal strength were made known by the central server 12, is suddenlymissing, this is reported to the central server 12. As a result, thefts,for example, can be prevented or at least noticed rapidly. Expediently,the position of the respective receiving station with longitude andlatitude is detected during the setting up of the emergency call system1 and is stored in the respective receiving station 4 to 6 or in thecentral server 2. Moreover, a defect of one of the receiving stations 4to 6 can thereby be rapidly deduced. Furthermore, if one of thereceiving stations 4 to 6 has been stolen and reactivated elsewhere,then this is detected by the receiving stations in the vicinity, whichreport to the central server 12 the fact that an unexpected receivingstation has appeared. As a result, stolen receiving stations can also befound again.

According to an exemplary embodiment of the invention, the emergencycall system 1 is configured in such a way that when an emergency callarrives, the central server 12 controls the receiving stations locatedin the vicinity of the mobile device to transmit via WLAN a warningmessage to mobile radio devices that are likewise moving in the WLANnetwork, such that on the smartphone of a passer-by, for example, theindication about a triggered alarm in the latter's vicinity is alsoindicated. This is advantageous particularly if a silent alarm wastriggered by the user 2.

The mobile device 3 may also have a vibration device which confirms anactuation of the emergency call switch 8 by single or repeatedvibration, depending on the type of actuation of the emergency callswitch 8. Moreover, a vibration may confirm the triggering of a silentalarm at one of the receiving stations 4 to 6.

When no receiving station is in the transmission range of the mobiledevice 3 at the point in time of the actuation of the emergency callswitch 8, the mobile device 3 transmits the emergency call until a firstreceiving station is detected if the user continues to move with themobile device 3, for example, and enters the reception range of areceiving station. So that the emergency call is then subsequentlytransmitted, and the alarm signal is triggered. If there is adisturbance of the communication of the receiving stations 4 to 6 by thelocal area network to the central server 12, then on account of theabove-described configuration of the emergency call transmitter 1 analarm signal can also be triggered independently of the central server12. This is the case if the data required for this purpose aretransferred from the central server 12 to the receiving stations 4 to 6at regular intervals and a connection to the central server 12 isrequired only for updating and for forwarding a received emergency callto the central server 12.

According to an exemplary embodiment of the invention, the receivingstations 4 to 6 are configured as routers that simultaneously providethe user of the emergency call system with access to the internet(hotspot). Moreover, it is possible to enable the use of the hotspotsprovided by the receiving stations 4 to 6 for third-party users who arenot registered in the emergency call system 1. The communicationconnection to the local area network can be effected by the respectiverouter or the respective receiving station 4 to 6 likewise by radio orin a wired manner. As an alternative to the configuration of the radiomodules 10, 11 of the emergency call system 1 as WLAN modules, it isalso conceivable for the radio modules 10, 11 to be configured asBluetooth modules.

The emergency call system 1 may be additionally configured in such a waythat the central server 12 can trigger an alarm signal at a plurality ofthe receiving stations, for example in order to warn againstfar-reaching dangers such as, for example, tornadoes, persons runningamok, or the like, that are moving through the area of the emergencycall system 1.

The respective receiving stations 4 to 6 may optionally be provided witha camera device which is activated after the reception of an emergencycall in order also to carry out an image transmission of the event tothe central server 12. According to another exemplary embodiment of themobile device 3 illustrated in FIG. 2, the mobile device 3 may also beconfigured as a wristwatch, a cellular phone or the like. With themobile device 3, the user can request help not only for himself/herselfbut also for persons in his/her vicinity. In this case, the user 2 canfirstly be sure that he/she will not be identified as the originator ofthe alarm signal, such that the user does not put himself/herself indanger if the user triggers the alarm for a third party. This possiblylowers the inhibition threshold for triggering an alarm signal in adangerous situation for users of the emergency call system 1. Therespective mobile device 3 is expediently assigned to a specific person,such that after the triggering of an emergency call, the person, ifhe/she has already moved away from the location of the event beforehelpers arrive, can also be questioned afterward. Misuse of theemergency call system 1 is also avoided as a result.

The emergency call system 1 is also suitable for areas in which nomobile radio network is available for transmitting an emergency call.Moreover, it can be employed where a receiving station is not connectedto a local area network (LAN). Instead the receiving station for examplerelays the alarm by WLAN to the closest receiving station that is itselfconnected to the local area network.

In accordance with a further exemplary embodiment, a cellular phone ofthe user 2 is configured to communicate with the mobile device 3, inparticular with the USB stick, in a wireless manner via the WLAN module(wired communication is alternatively likewise conceivable). In thiscase, the mobile device 3 has, in addition to the radio module 10configured as a WLAN module, a further radio module configured as aBluetooth module. For the case where the user 2 is located in anenvironment in which no receiving station is in the reception range ofthe WLAN module or of the radio module, the mobile device 3 changes tothe driving of the second radio module or of the Bluetooth module inorder to transmit the emergency call to the cellular phone of the userby the Bluetooth module. In this case, the cellular phone is programmedin such a way that, if it detects the emergency call of the mobiledevice 3, via the mobile radio network in which the cellular phoneusually communicates, it can forward the emergency call to a or theemergency call center and in this case, in particular, communicateposition data of the mobile device 3 and/or of the cellular phoneitself. As a result, at least help can be requested upon the triggeringof the mobile device 3, without this being noticed by a potentialattacker. In accordance with an exemplary embodiment of the invention,the receiving station which, with knowledge of the communicated positiondata of the mobile device 3, is closest to the mobile device 3, isdriven remotely by the emergency call center in order to output thealarm signal.

It is understood that the foregoing description is that of the preferredembodiments of the invention and that various changes and modificationsmay be made thereto without departing from the spirit and scope of theinvention as defined in the appended claims.

What is claimed is:
 1. A method for operating an emergency call systemhaving at least one mobile device and a plurality of receiving stations,the at least one mobile device being carried by a user and having atleast one mobile device radio module configured to transmit an emergencycall, each of the plurality of receiving stations having at least onereceiving station radio module and an alarm device and being configuredas a router, the at least one receiving station radio module beingconfigured to receive the emergency call from the at least one mobiledevice, and the alarm device being configured to output an acousticand/or visual alarm signal, the method comprising: transmitting theemergency call from the at least one mobile device to a first of theplurality of receiving stations to trigger the alarm signal; determininga position of the at least one mobile device relative to the pluralityof receiving stations; and, depending on the determined position of theat least one mobile device, selecting only one of the plurality ofreceiving stations which is best suited to direct an attention of athird party to the user and to trigger the alarm signal of the selectedreceiving station's alarm device to attract the attention of the thirdparty in a vicinity of the selected receiving station.
 2. The method ofclaim 1, further comprising: sending a notification to mobile devices ofusers connected to a same network of the selected receiving station whenthe emergency call is received.
 3. The method of claim 1, wherein: theemergency call system includes a central server, and the method furthercomprises: when the emergency call is received, controlling receivingstations located in a vicinity of the at least one mobile device by thecentral server to transmit via a network of the receiving stations awarning message to mobile radio devices connected to the network andmoving in the range of the network.
 4. The method of claim 1, furthercomprising: determining, by the least one mobile device, signalstrengths of receiving station radio modules of the plurality ofreceiving stations; and, transmitting the emergency call to one of theplurality of receiving stations having a receiving station radio modulethat has a highest signal strength.
 5. The method of claim 4, furthercomprising: transmitting, by the least one mobile device, the signalstrengths of all of the plurality of receiving stations together withthe emergency call to the first of the plurality of receiving stations;and, determining, by the first of the plurality of receiving stations,the position of the at least one mobile device depending on said signalstrengths.
 6. The method of claim 1, further comprising: comparing, bythe first of the plurality of receiving stations, the signal strengthswith reference signal strengths; and, triggering the alarm signal by thefirst of the plurality of receiving stations only if the signalstrengths correspond to one or more of the reference signal strengths.7. The method of claim 1, further comprising: to set up the emergencycall system at different positions, storing reference signal strengthsof a reference mobile device, respectively detected by the plurality ofreceiving stations, together with position data of the reference mobiledevice that are determined by a global navigation satellite system. 8.The method of claim 1, further comprising: subsequent to receiving theemergency call by the first of the plurality of receiving stations,forwarding the emergency call, an identifier of the mobile device andposition data of the first of the plurality of receiving stations and/orof the at least one mobile device by the first of the plurality ofreceiving stations to a central server.
 9. The method of claim 1,further comprising: to set up the emergency call system, preselectingone of the plurality of receiving stations that is within a range of areference mobile device to trigger the alarm signal as reference signalstrengths are determined depending on a position of the reference mobiledevice.
 10. The method of claim 1, further comprising: to set up theemergency call system, storing in the plurality of receiving stationsposition data of neighboring receiving stations; and, depending on theposition of the at least one mobile device, triggering the alarm signalby the first of the plurality of receiving stations or forwarding theemergency call by the first of the plurality of receiving stations to aneighboring second receiving station if a position of the neighboringsecond receiving station is nearer to the position of the at least onemobile device than a position of the first of the plurality of receivingstations or a position of a preselected receiving station.
 11. Themethod of claim 1, further comprising: depending on a type of thetransmitted emergency call, triggering a silent alarm or a loud alarm bythe one of the plurality of receiving stations.
 12. The method of claim1, wherein, with their respective receiving station radio modules, theplurality of receiving stations scan their surroundings to detectneighboring receiving stations.
 13. The method of claim 1, wherein theat least one mobile device, with the transmission of the emergency call,starts an audio recording and transmits audio data packets at regulartime intervals to the first of the plurality of receiving stationsand/or to at least one further receiving station.
 14. The method ofclaim 1, wherein a user identifier or a mobile device identifier isconcomitantly transmitted with the emergency call by the at least onemobile device.
 15. The method of claim 14, wherein an alarm signal istriggered only if the user identifier or the mobile device identifiercorresponds to an authorized user identifier or a corresponding mobiledevice identifier stored in the central server or in the first of theplurality of receiving stations.
 16. An emergency call systemcomprising: at least one mobile device being carried by a user andhaving an emergency call switch and at least one mobile device radiomodule configured to transmit an emergency call; a plurality ofreceiving stations each having at least one receiving station radiomodule and being configured to receive the emergency call; the at leastone mobile device being configured to trigger an emergency call and,upon an actuation of the emergency call switch, to transmit theemergency call to one of the plurality of receiving stations which isbest suited to direct an attention to the user; each of the plurality ofreceiving stations being configured as a router and having an alarmdevice and a control unit; the alarm device being configured to outputan acoustic alarm signal and/or a visual alarm signal; and, the controlunit being configured to determine a position of the mobile devicedepending on a signal strength of at least one of the receiving stationradio module and the mobile device radio module, and, depending on thedetermined position, to output an alarm signal by only one of the alarmdevices to attract the attention of a third party in a vicinity of theone of the plurality of receiving stations.
 17. The emergency callsystem of claim 16, wherein a notification is sent to mobile devices ofusers connected to a same network of the one of the plurality ofreceiving stations when the emergency call is received.
 18. Theemergency call system of claim 16, further comprising a central server,wherein, when the emergency call is received, the central servercontrols receiving stations located in a vicinity of the at least onemobile device to transmit via a network of the receiving stations awarning message to mobile radio devices connected to the network andmoving in the range of the network.
 19. The emergency call system ofclaim 16, wherein the radio modules are configured as WLAN modules orBluetooth modules.
 20. The emergency call system of claim 16, whereinthe emergency call system is configured to: transmit the emergency callfrom the at least one mobile device to a first of the plurality ofreceiving stations to trigger the alarm signal; determine a position ofthe at least one mobile device relative to the plurality of receivingstations; and, depending on the determined position of the at least onemobile device, select only one of the plurality of receiving stations totrigger the alarm signal.